MISO-SPP IPSAC 10/24/25: MISO-SPP Interregional Planning Updates, MISO-SPP Queue Alignment, and Interconnection Coordination

The MISO-SPP IPSAC meeting convened the on October 24, 2025, to review ongoing coordination efforts between the two Regional Transmission Organizations. The session highlighted progress on joint transmission studies, queue alignment initiatives, and the evaluation of renewable energy projects impacting both regions.

With load growth accelerating and renewable development clustering near RTO boundaries, the MISO-SPP relationship continues to evolve toward a more integrated approach. The October meeting underscored the shared priorities of both organizations: improving interregional transfer capability, aligning study assumptions, and establishing long-term processes that reduce congestion while enhancing reliability.

MISO-SPP Interregional Planning Updates

A major topic of discussion was the status of ongoing interregional transmission studies and their implications for MISO’s MTEP25 and SPP’s ITP25 planning cycles. These studies form the analytical foundation for identifying future high-voltage projects that strengthen connectivity between the two systems. Key points included:

• Joint Study Coordination: MISO and SPP are advancing coordinated assessments that examine congestion patterns and bulk power transfer limitations along key seams, particularly in the central and southern interface zones.
• Long-Range Transmission Planning Integration: Both RTOs are evaluating how their individual long-range planning initiatives can inform interregional project selection. This includes identifying corridors capable of supporting renewable energy export and import flows over the next two decades.
• Congestion Relief Focus Areas: Persistent congestion along 345 kV tie lines and transformer-limited interfaces remain priority targets for potential interregional upgrades.
• Economic and Reliability Drivers: Joint analyses are now considering a broader set of benefits — including production cost savings, curtailment reduction, and resilience under extreme weather scenarios — rather than purely economic congestion relief.

This approach signals a cultural shift within both MISO and SPP, recognizing that transmission investment must serve multiple purposes simultaneously: reliability, flexibility, and decarbonization support.

MISO-SPP Queue Alignment and Interconnection Coordination

The IPSAC reviewed progress on MISO-SPP queue alignment — a critical issue as renewable developers continue submitting interconnection requests that straddle both RTO territories. The goal is to create a consistent framework that reduces duplication and timing mismatches across the seams. Highlights included:

• Cluster Timing Coordination: MISO and SPP are exploring mechanisms to align interconnection cluster timelines, enabling developers with projects near the regional border to participate in synchronized study windows.
• Data and Model Consistency: Both RTOs are harmonizing key modelling parameters — including load forecasts, renewable profiles, and generation retirements — so that interconnection results are more directly comparable.
• Deliverability Alignment: A new joint effort aims to ensure that interconnection results account for deliverability and transfer limitations between regions, minimizing post-study surprises for developers.
• Joint Study Efficiency: The IPSAC confirmed that future interregional projects will leverage a shared study platform to streamline analysis and reduce stakeholder review time.

For developers operating along the MISO-SPP seam, this coordination could significantly reduce uncertainty, improve transparency, and accelerate project readiness.

Transmission Planning Coordination

The IPS also reviewed updates on coordination between interconnection studies and the MISO Transmission Expansion Plan (MTEP25). MISO is working to align its reliability and policy-driven transmission upgrades with the interconnection needs emerging from the queue. Key discussion points:

• Integrated Modelling Framework: Interconnection studies are increasingly drawing from the same data and assumptions used in the regional transmission plan, ensuring consistency between system upgrades and generator requests.
• Holistic Grid Expansion: MISO planners emphasized that new transmission projects identified under MTEP25 are expected to address multiple drivers—reliability, congestion relief, renewable deliverability, and long-term policy needs.
• Interregional Coordination: Ongoing collaboration with neighboring RTOs (PJM, SPP, and others) continues to refine import/export capability assumptions and avoid duplicative upgrades.
• Future Alignment with FERC Order 1920: The subcommittee discussed the forthcoming integration of long-term transmission planning rules into interconnection processes, emphasizing more transparent cost allocation and improved forecasting of generation siting trends.

This integration ensures that MISO’s interconnection reforms do not occur in isolation but rather within the broader context of long-term regional planning and reliability assurance.

MISO-SPP Renewable Integration and Market Efficiency

Another major discussion theme centered on the influx of renewable generation across both footprints and its effect on market efficiency and operational reliability. Both RTOs are seeing rapid increases in solar, wind, and hybrid battery projects that rely on interregional transmission to reach load centers. Key observations:

• Renewable Growth Near Seam Zones: Much of the renewable development in states such as Missouri, Arkansas, and Oklahoma sits close to the MISO-SPP boundary, where transmission congestion is already significant.
• Curtailment Reduction Potential: Interregional upgrades are projected to deliver meaningful reductions in renewable curtailment, particularly during high-generation, low-load periods.
• Market Coordination: The RTOs are exploring ways to enhance market-to-market coordination during congestion events, improving redispatch efficiency and ensuring both markets capture the benefits of increased transfer capability.
• Grid Flexibility Initiatives: Energy storage and flexible hybrid resources are being considered in upcoming studies as transmission-supporting assets, capable of stabilizing frequency and voltage across seams.

Together, these initiatives reflect a long-term vision: building an adaptable, interconnected grid that supports both RTOs’ decarbonization trajectories.

Modeling Enhancements and Future Planning Cycles

The IPSAC also addressed technical enhancements to system modeling and the synchronization of future MISO-SPP planning cycles. Both organizations emphasized that interregional planning must remain data-driven and forward-looking.

• Scenario Alignment: MISO and SPP are developing shared scenario assumptions for high-renewable, extreme-weather, and high-load growth futures.
• Transmission Topology Updates: Seam interfaces will be modeled with more accurate dynamic response characteristics, improving study precision.
• Public Data Transparency: Each RTO committed to publishing more accessible study documentation, allowing stakeholders to evaluate the underlying assumptions used in interregional project screening.

These steps will make the interregional planning process more predictable and collaborative, supporting faster decision-making and better long-term investment planning.

Key Takeaways from the MISO-SPP IPSAC Meeting

The October 2025 MISO-SPP IPSAC meeting delivered several clear takeaways:

1. Transmission coordination is accelerating. Interregional planning is now embedded in both RTOs’ long-range frameworks, aligning MTEP and ITP priorities.
2. Queue alignment is a shared priority. Developers can expect more consistent study timing, data assumptions, and deliverability assessments across the seam.
3. Renewable congestion remains a top driver. Transmission expansion is essential for reducing curtailment and unlocking stranded renewable capacity.
4. Transparency is improving. MISO and SPP are expanding stakeholder access to model data and planning assumptions, reducing ambiguity around project selection.

For developers and asset owners, these developments point to a maturing interregional process — one that will favor well-modeled, strategically located projects capable of leveraging future transmission expansion. Our experts help renewable developers, investors, and utilities navigate the evolving MISO-SPP interregional planning and interconnection landscape. Whether you’re developing hybrid resources near the seam, evaluating transmission congestion risks, or preparing deliverability analyses, our team ensures your projects align with the latest RTO planning standards.

ZEG’s expertise spans interconnection strategy, grid-readiness assessments, and policy-driven planning alignment — giving your team the insight to make informed, bankable decisions.

Contact ZEG today to discuss how the outcomes of the October 2025 MISO-SPP IPSAC meeting may influence your transmission, interconnection, or renewable portfolio strategy — and ensure your projects are positioned for success in both markets.

For more on the MISO-SPP IPSAC, MISO-SPP Interregional Planning updates, MISO-SPP Queue Alignment, and Interconnection Coordination view Meeting Materials here.